Center for Functional Nanomaterials Seminar

Metallic glasses (MGs) have exciting potential for structural, chemical, and magnetic applications with the sizes ranging from micrometers to centimetres, but the fabrication and characterization down to nanoscale remains an important challenge. Progress has been hindered by the lack of bottom-up methodologies to produce amorphous nanostructures. Recently, we show that the self-organized amorphous nanowires that are formed on the fracture surfaces of bulk metallic glasses [Nakayama et al., Nano Lett. 8, 516-519 (2008)]. However, it is difficult to control their morphologies because they were created by instantaneous fracture processes. Here we first report the controlled formation and mechanical characterization of individual amorphous nanowires. We find that they have a high strength with the excellent flexibility where the elastic modulus is much smaller than that of the bulk owing to the hyper-excess free volume in nanowire. The versatility of the drawing process ensures that MGs of a broad range of compositions can be formed, depending on the composition elements used. In terms of future applications, Pd-based MG nanowires could be used as sensors with high hydrogen sensitivity. FeCo-based MG on the other hand exhibits soft magnetic properties that could be used for ultrahigh magnetic-field sensors in biomagnetic measurements.